Evaluation of outcome after acute carbon monoxide poisoning by brain CT.

Of 129 patients with carbon monoxide (CO) poisoning, 62(48.0%) had characteristic computed tomographic (CT) findings. The most common finding, seen in 42 patients, was low-density in the cerebral white matter, and the second characteristic feature, seen in 33 patients, was low-density in both globus pallidi. Abnormal CT findings tended to increase in accordance with the duration of unconsciousness during acute CO poisoning, but such findings occurred even when the mental state was clear during acute illness. The prognosis of acute CO poisoning depended on low-density lesions of the cerebral white matter rather than those of the globus pallidus. There also seemed to be a significant correlation between the cerebral white matter changes in the initial CT scan and the development of delayed neurologic sequelae after acute CO poisoning, particularly in middle age or older patients, but no correlation between the CT findings and the clinical outcome of delayed neurologic sequelae.     

Interictal brain 99m Tc-HMPAO SPECT study in chronic epilepsy

We performed interictal brain 99m Tc-HMPAO study in eight cases of chronic epilepsy. SPECT (single photon emission computed tomography) study showed abnormality in seven cases. As compared to computed tomography (CT) scan and electroencephalogram (EEG) which were positive in 25% and 62% cases respectively it showed abnormality in 87%. In two cases where CT scan and EEG both were normal, SPECT showed areas of hypoperfusion. In one case where EEG indicated a bilateral focus, SPECT study showed a clearly defined unilateral focal hypoperfusion defect. Areas of hyperperfusion were not seen in any of our cases. Our results indicate that HMPAO SPECT is more sensitive than CT scan and EEG, in localising an epileptogenic focus in cases of chronic epilepsy.     

Episodic diencephalic hypoperfusion in Kleine-Levin syndrome

A 22 year-old woman suffered from recurrent episodes of hypersomnia, apathy, and hyperphagia. The symptoms occurred 3 to 4 times per year, and each attack lasted 2 to 3 weeks. 99mTc-ethylcysteinate dimer brain single photon emission computed tomography (SPECT) was performed during symptomatic and asymptomatic periods. To localize brain regions with perfusion changes during symptomatic period, asymptomatic SPECT was subtracted from symptomatic SPECT. The subtracted SPECT showed significant hypoperfusion in the left hypothalamus, bilateral thalami, basal ganglia, bilateral medial and dorsolateral frontal regions, and left temporal lobe during the symptomatic period. These cerebral hypoperfusion areas support the diencephalic hypothesis and clinical symptoms of Kleine-Levin syndrome.     

Thalamic syndrome and cortical hypoperfusion on technetium-99m HM-PAO brain SPECT

The six patients included in this study had painful dysesthesia, resulting from vascular lesions in or near the thalamus, confirmed by computerized tomography(CT) brain scan. Using hexamethyl propyleneamine oxime(HM-PAO) single photon emission computed tomography(SPECT) brain scanning, regional cerebral perfusion(rCP) was demonstrated. In contrast to three patients with lesions near the thalamus who showed symmetrical cortical radioactivity, the other three patients with thalamic lesions revealed decreased rCP in the ipsilateral cerebral cortex on HM-PAO brain SPECT. We thought that the loss of afferent activating stimuli from the thalamus led to decreased cortical neuronal activity and the following hypoperfusion. In patients with thalamic syndrome resulting from thalamic lesions, the role of the remote effect of the thalamic damage and consequent cortical deregulation in the development of thalamic pain and/or neuropsychological symptoms cannot be excluded completely.     

The relationship of SPECT scans to behavioral dysfunction in neuropsychiatric patients.

The authors describe 20 neuropsychiatric inpatients consecutively evaluated in the context of routine clinical care. Patients had both a neurological and psychiatric disorder. Each was clinically evaluated as part of a psychiatric hospitalization. DSM-III-R diagnoses, electroencephalograms, magnetic resonance imaging (MRI) or computed tomography (CT) scans of the brain, single photon emission computed tomography (SPECT) scans of the brain, and cognitive testing are reported. In only three cases were SPECT, MRI (or CT), and electroencephalogram all normal. SPECT abnormalities were associated with behavioral and cognitive presentations and with the hypothesized anatomical areas of dysfunction in 16 cases. In six cases SPECT and MRI were equivalent, involving structural lesions or normal scans. In only one case did MRI (or CT) detect deficits not revealed by SPECT, which were nonspecific white matter lesions and atrophy. The authors conclude that SPECT scans may be superior to structural brain scans in detecting clinically relevant deficits in neuropsychiatric patients, particularly when physiological lesions are involved.     

SPECT changes and their correlation with EEG changes in tuberculous meningitis

OBJECTIVE: In tuberculous meningitis (TBM) blood flow may be altered due to associated vasculitis, hydrocephalus and raised intracranial pressure. Electroencephalography (EEG) and single photon emission computed tomography (SPECT) provide information about electrical activity and regional cerebral blood flow respectively. This study aims at the correlation of EEG and SPECT changes in patients with TBM. METHOD: Sixteen patients with TBM whose age ranged between 5 and 62 years and 3 of whom were females were subjected to clinical, radiological (CT and/or MRI), EEG and SPECT studies using 99mTc ethylene cystine dimer (ECD). Ten patients were in stage III and 3 each in stage II and stage I meningitis. Cranial CT scan was carried out in 15 and MRI in 4 patients. Hydrocephalus was present in 9, infarction in 7 and tuberculoma in 5 patients. RESULTS: SPECT studies were abnormal in all except 2 patients revealing basal ganglionic hypoperfusion in 14 and focal cortical hypoperfusion in 9 patients. The EEG was abnormal in 11 patients which included delta slowing in 5, theta slowing in 6, frontal intermittent rhythmic delta activity (FIRDA) in 3 and epileptiform discharges in 2 patients. All the patients with abnormal EEG had abnormal SPECT study except 1. In 4 patients, EEG was normal although there was subcortical hypoperfusion on SPECT. In spite of high frequency of focal cortical hypoperfusion (9 patients), EEG revealed focal abnormality in 3 patients only. CONCLUSION: It can be concluded that the SPECT reveals more frequent abnormalities compared to EEG and CT scan. Cortical hypoperfusion with or without basal ganglia hypoperfusion is associated with FIRDA and diffuse delta slowing on EEG.     

Chorea following acute carbon monoxide poisoning

The clinical cases of 6 patients suffering with chorea after acute carbon monoxide (CO) poisoning were reviewed. There were 2 men and 4 women, and the age at onset ranged from 11 to 60 (mean 33.0) years. All the patients except one were associated with mild delayed CO encephalopathy. The latency period between CO poisoning and the onset of chorea was 10 to 30 (mean 21.7) days. The duration of chorea after CO poisoning was 14 to 90 (mean 39.8) days. The brain CT findings were bilateral low- density lesions in the basal ganglia and/or in the white matter of the cerebral cortex, and there was no correlation between the lesion sites on the imagings and the development of chorea. Neuroleptic agents alleviated the chorea and the patients did not relapse after neuroleptic agents were halted.     

SPECT显像在NPC放疗后所致脑损伤中的初步应用

目的 评价单光子发射型电子计算机断层（ＳＰＥＣＴ）脑血流灌注显像在鼻咽癌（ＮＰＣ）放射治疗后放射性脑损伤中的临床价值。方法 采用ＳＰＥＣＴ脑血流灌注显像检查,对１６例鼻咽癌放射治疗后有放射性脑损伤症状的患者和８例示经放疗的鼻咽癌患者作半定时分析对测量结果作统计学分析。１６例放射性脑损伤患者同期做电子计算机体层检查（ＣＴ）对比。结果 １６例有放射性脑损伤症状的鼻咽癌患者双侧颞叶局部脑血流灌注（ｒＣＢＦ）在横断面层面－放射性曲线相应部位上可见局部放射性下降峰或曲线变窄小,峰值降低,其曲线局部下降峰值与鼻咽癌放疗效量的生物效应剂量（ＢＥＤ）值呈正相关（ｒ＝０．８９７６,Ｐ〈０．０１）。８例未经放疗的鼻咽癌患者,在横断面图像上其双侧颞叶局部脑血流灌注的层面－放射性曲线大致呈正态分布曲线,未见异常的局部下降峰或曲线变窄小     

Automatic CT-SPECT registration of livers treated with radioactive microspheres

We have developed an automated technique to accurately register the CT and SPECT scans of the liver of patients treated with radioactive microspheres for tumour targeting assessment. An anthropomorphic phantom was used to validate the accuracy of the registration algorithm. The phantom liver and three fiducial markers placed on its surface were filled with 99mTc. The phantom was scanned with CT and SPECT scanners in different positions. The liver volume was contoured on the CT scans from which a three-dimensional liver mask was created. By constraining the liver volume to the volume obtained from the CT scans, another liver mask was automatically created from the SPECT images. An adaptive simulated annealing algorithm was used to minimize the difference between the two volumes formed by the two sets of masks. The algorithm involved rigid transformation of the SPECT mask to reach the optimization goal. The accuracy of the algorithm was evaluated by the superposition of the fiducial markers on the CT and SPECT. The registered SPECT overlaid on the CT scan of the phantom showed congruence of the fiducial markers on CT and SPECT images within 1 mm. The technique was applied to a patient image set who received the microsphere infusion procedure. The registered CT and SPECT images of the patient showed that the majority of the activity was concentrated in the tumour, indicating a successful tumour targeting.     

99Tcm-MIBI SPECT/CT同机融合显像对脑肿瘤的诊断价值

目的 与单纯SPECT显像或单纯CT显像进行对比研究,探讨99Tcm-MIBI SPECT/CT同机融合显像对脑肿瘤良恶性判断的临床应用价值.方法 对45例临床疑似脑肿瘤的患者行99Tcm-MIBI SPECT显像,CT显像及99Tcm-MIBI SPECT/CT同机融合显像.以术后病理结果为准,分别计算出以上三种方法对脑肿瘤定性诊断的灵敏度、特异性、准确性,通过统计学方法将融合显像结果分别与单一显像结果进行对比分析.结果 SPECT/CT融合显像与单纯SPECT显像相比,灵敏度（x2 =4.383,P＜0.05）、特异性（x2=3.949,P＜0.05）、准确性（x2=8.073,P＜0.01）均明显提高,差异有统计学意义.SPECT/CT融合显像与单纯CT显像相比,灵敏度（x2=5.543,P＜0.05）、特异性（x2=5.100,P＜0.05）、准确性（x2=10.497,P＜0.01）均明显提高,差异有统计学意义.结论 99Tcm-MIBI SPECT/CT同机融合显像对脑肿瘤的诊断较单一显像具有更高的诊断价值.     

Hyperglycemia exacerbates brain damage in acute severe carbon monoxide poisoning

It is hypothesized that hyperglycemia naturally induced by stress and/or produced by intravenous trauma therapy adversely effects neurologic outcome following acute severe carbon monoxide poisoning, and the higher the blood glucose the greater the degree of brain dysfunction. Increased availability of glucose presumably increases cerebral glycolytic flux, and elevates intracellular and interstitial lactate level, which in turn induces acidosis and edema, resulting in brain damage. In a retrospective study of blood glucose and other data obtained from patients upon hospital admission for CO poisoning, a mean value of 409 mg/dL was associated with "brain death", a value of 215 mg/dL with "minimal to substantial brain damage," and a value of 165 mg/dL with "normal" recovery.     

SPECT/CT脑血流灌注显像的临床应用进展

SPECT/CT脑血流灌注显像是SPECT(单光子发射计算机断层显像)技术和CT(计算机断层扫描技术)同机融合的一种检查方法,能够将解剖显像与功能显像完美的结合在一起,提高定位准确率的同时还可以对疾病进行多角度的分析,兼具了SPECT灵敏度高和CT特异性、分辨率高的优点,因此,对很多疾病如脑梗、TIA、癫痫等缺血性病变的病灶定位、治疗指导和预后评估以及正常脑功能的研究有着独特的优势.本文结合国内外资料对SPECT/CT脑血流灌注显像的原理、技术和临床应用的进展进行综述.     

Assessment of regional cerebral blood flow (rCBF) in ischemic stroke using Tc-99m HMPAO SPECT--comparison with CT and MR findings

To assess the regional cerebral blood flow (rCBF) in ischemic stroke, we analyzed the findings of single photon emission computed tomography (SPECT) using technetium-99m hexamethyl propyleneamine oxime (Tc-99m HMPAO). The SPECT images revealed abnormal areas of decreased perfusion in 29 out of 31 subjects (93.5%), which represented a higher detection rate than those for CT and MR (89.5%, respectively). Also, the areas of decreased perfusion were frequently larger than the lesions on CT and MR. Areas of decreased perfusion remote from the CT/MR lesions were found in 10 patients, including 8 with crossed cerebellar diaschisis (CCD). Thus, studies of rCBF by Tc-99m HMPAO SPECT can be useful in the assessment of ischemic stroke.     

99Tcm-MIBI SPECT/CT联合外周血 β2-微球蛋白对脑肿瘤鉴别诊断的价值研究

目的 探讨99Tcm-MIBI SPECT/CT联合外周血中的β2-微球蛋白(β2-M)对脑肿瘤良恶性判断的临床价值研究.方法 对53例脑肿瘤的患者行99Tcm-MIBI SPECT/CT显像,并于手术前采血测试其中β2-微球蛋白的含量,以术后病理为准,通过计算及统计学比较,对以上两种方法及二者的联合诊断对脑肿瘤定性诊断的效能进行分析与比较.结果 99 Tcm-MIBI SPECT/CT和外周血中的β2-M及联合诊断的灵敏度、特异性、准确性分别为68%、71.4%、69.8%,72%、64.3%、67.9%,92%、92.9%、92.5%.结论 99 Tcm-MIBISPECT/CT显像联合外周血β2-M对鉴别诊断脑肿瘤良恶性较单一方法具有更好的临床应用价值.     

CO中毒后迟发性脑病的临床与脑电图、脑CT分析

目的：探讨CO中毒后迟发性脑病的EEG和脑CT特征及对本病的诊断价值。方法：对63例CO中毒后迟发性脑病的临床与脑电图、脑CT特征进行分析。结果：CO中毒后迟发性脑病的临床主要表现为以痴呆为主的精神障碍，EEG表现为以额叶为主的广泛弥漫性高幅慢波及生理波减弱，阳性率为100％。脑CT主要以皮质下广泛的低密度改变及基底节区局灶性低密度影为特征，部分患CT可正常。结论：EEG和CT能发现CO中毒引起的脑部形态及功能的变化，EEG对DEACMP的敏感性高于CT，EEG在早期诊断DEACMP上优于CT，可作为临床痊愈、判断预后的指标之一。     

Rodent brain imaging with SPECT/CT

We evaluated methods of imaging rat models of stroke in vivo using a single photon emission computed tomography (SPECT) system dedicated to small animal imaging (X-SPECT, Gamma Medica-Ideas, Northridge, CA). An animal model of ischemic stroke was developed for in vivo SPECT/CT imaging using the middle cerebral artery occlusion (MCAO) technique. The presence of cerebral ischemia was verified in ex vivo studies using triphenyltetrazolium chloride (TTC) staining. In vivo radionuclide imaging of cerebral blood flow was performed in rats following MCAO using dynamic planar imaging of 99mTc-exametazime with parallel hole collimation. This was followed immediately by in vivo radionuclide imaging of cerebral blood flow with 99mTc-exametazime in the same animals using 1-mm pinhole SPECT. Correlated computed tomography imaging was performed to localize radiopharmaceutical uptake. The animals were allowed to recover and ex vivo autoradiography was performed with separate administration of 99mTc-exametazime. Time activity curve of 99mTc-exametazime showed that the radiopharmaceutical uptake could be maintained for over 9 min. The activity would be expected to be relatively stable for a much longer period, although the data were only obtained for 9 min. TTC staining revealed sizable infarcts by visual observation of inexistence of TTC stain in infracted tissues of MCAO rat brains. In vivo SPECT imaging showed cerebral blood flow deficit in the MCAO model, and the in vivo imaging result was confirmed with ex vivo autoradiography. We have demonstrated a capability of imaging regions of cerebral blood flow deficit in MCAO rat brains in vivo using a pinhole SPECT dedicated to small animal imaging.     

Corpus callosum atrophy and neuropsychological outcome following carbon monoxide poisoning.

This study assessed the effects of carbon monoxide (CO) poisoning on the corpus callosum (CC). Sixty-two CO-poisoned patients had MRI scans and a battery of neuropsychological tests within 24 h (day of exposure) of CO poisoning and at 6 months post CO exposure. Serial quantitative magnetic resonance imaging (QMRI) analysis of the CC was carried out, with the day of exposure scans compared to the 6-month scans. There was no difference between normal subjects' CC and the baseline scans in the CO-poisoned patients. We detected a 15-mm2 loss in the cross-sectional surface area of the CC between baseline and the 6-month follow-up scans. The effect on the CC was generalized atrophy rather than CC subregion-specific changes. Neuropsychological test results performed at baseline and at 6 months did not correlate with the level of CC atrophy. Independent of any CC effects, the patients exhibited impaired memory, attention, and executive functioning on baseline testing, with variable improvement in cognitive function at 6 months. Quantitative MRI analysis allows for the detection of subtle CC changes that may not otherwise be observed following CO poisoning. The long-term effects of CO on the brain have been historically underestimated; however, we found subtle but significant CC atrophy and cognitive impairments following CO poisoning.     

Combined 99mTc-ECD SPECT and neuropsychological studies in MCI for the assessment of conversion to AD

Identifying pre-clinical Alzheimer's disease (AD) in subjects with mild cognitive impairment (MCI) is a major issue in clinical diagnosis. Establishing a combination of predictive markers from different fields of research might help in increasing the diagnostic accuracy. Aim of this study was to evaluate the potential role of 99mTc-ECD single photon emission computed tomography (SPECT) and memory scores in predicting conversion to AD in MCI subjects. Thirty-one MCI subjects underwent a clinical and neuropsychological examination, and a regional cerebral blood flow (rCBF) SPECT scan at baseline. Subjects had been followed periodically through 2 years in order to monitor the progression of cognitive symptoms. Canonical variate analysis of principal components was able to separate all subjects who converted to AD from those who remained stable, the former being characterized by a specific hypometabolic pattern, involving the parietal and temporal lobes, precuneus, and posterior cingulate cortex. Canonical correlation analysis of combined baseline memory deficits and rCBF SPECT images identified pre-clinical AD with a sensitivity and specificity of 77.8%. The pattern of hypoperfusion 99mTc-ECD SPECT and the severity of memory deficits predict the risk of progression to probable AD dementia in MCI subjects.     

Subclinical brain swelling in children during treatment of diabetic ketoacidosis

Clinically apparent cerebral edema is a rare and often fatal complication of diabetic ketoacidosis. To determine whether subclinical brain swelling occurs more commonly, we obtained cranial CT scans in six children with diabetic ketoacidosis treated with fluid resuscitation and continuous low-dose insulin therapy. Control scans were obtained before hospital discharge. Compared with the scans during convalescence, the early scans of all six children showed a narrowing of the brain's ventricular system, compatible with brain swelling. Average changes in diameter were 1.3 +/- 0.1 mm for the third ventricle and 3.7 +/- 0.8 mm for the lateral ventricles (P less than 0.01). In addition, a narrowing of the subarachnoid spaces was subjectively noted during a blind reading of the early scans. Although no single scan was overtly indicative of cerebral edema, the data suggest that subclinical brain swelling may be a common occurrence during treatment of diabetic ketoacidosis in children. Sequential CT scans of the brain may provide a means of evaluating modifications of standard therapy aimed at preventing cerebral edema.     

Pathophysiology of brain injuries in acute carbon monoxide poisoning: A novel hypothesis

Acute carbon monoxide (CO) poisoning causes the neurologic symptoms and brain lesions during both acute and delayed phase. We propose that catecholamine crises in globus pallidus and deep white matter are the key pathophysiological factors causing acute and delayed brain injuries respectively. Increased sympathetic activities due to acute CO poisoning is followed by increases of catecholamine levels in synapses or nerve terminals in organs including the brain, especially, limbic system. A dopamine excess in the synaptic cleft of the mesolimbic system, including globus pallidus, may cause the destruction of synapses and nuclei in the globus pallidus. Consequently, the striatal lesion is affected in the acute phase of CO intoxication. Moreover, an increase of catecholamine levels in synapses of deep white matter can persist after the acute stage of CO intoxication. A dopamine excess could lead to oxidative metabolism of dopamine, serotonergic axonal injury, or secondary myelin damage.